The present invention generally relates to constant false alarm rate (CFAR) signal processors, and in particular, to a CFAR which determines a threshold level based upon accumulated statistics.
In prior art, CFARs have been developed which use a range cell or range gate averaging technique. These CFARs average the data from cells near a test cell with the assumption that the terrain and environmental conditions covered by these cells are similar to the terrain and environmental conditions of the test cell. The difficulties with this type of CFAR are that terrain conditions may vary drastically from one cell to the next. This could result in a threshold level being set too high for the test cell and masking actual targets. Another problem is multiple targets. Using cell averaging techniques, if there are subsequent targets located in the cells to be averaged, they may cancel out a target located in the test cell. In CFAR using cell averaging, in order to obtain an acceptable false alarm rate, threshold levels may be higher than necessary due to inaccuracies in terrain and environmental conditions data resulting in a reduced probability of target detection.